Process for treating ores.



A. S. DWIGHT.

vPROCESS FOR TREATING oREs.

APPLICATION FILED JULY 7| 1913.

Patented Feb. 13, 1917.

3 SHEETS-SHEET l.

A. S. DWIGHT. PROCESS FOR TREATING ORES. APPLICATION FILED JULY 1. 191s.

Patented Feb. 13, 1917.

3 SHEETS-SHEET 2 UNITED STATES PATENT oEEIoE.

ARTHUR S. DWIGHT, OF NEW YORK, N. Y., ASSIGNOR T0 DWIGHT & LLOYDSINTERING COMPANY, OF. NEW YORK, N. Y., A CORPORATION OF DELAWARE.

PROCESS FOR TREATINGrA ORES.

Specification of Letters Patent.

Application led July 7, 193`; Serial No. 777,732.

forv Treating Ores, of which the following is a specification, referencebeing had therein to the accompanying drawing.

This invention relates to improvements in the treatment of an ore masswhichVY contains a combustible component, either one united chemicallywith ore ingredients, or one physically commingled, naturally orartificially, therewith, and from the treatment of which mass productscan be obtained that have a value supplemental to the value of themetallic components..

I shall refer to ore masses containing metallic suld, but it will beunderstood that these are to be regarded merely as types of a class anyone of which can be subjected successfully to\ the treatment that I4have devised. o.

These suld ores have been preliminarily treated by one o-r another ofvarious methods. The principal characteristic of these is' termedfroastingf In the roasting practice that has been most frequentlyfollowed the ore, either in theform of native fines or as concentrates,is spread on an elongated hearth. While there exposed it is brought to asulfur-disassociating temperature by the products of combustion of anadjacent fire bed or furnace; and, simultaneously, air is passed inlarge volumes over the upper sur-` -face of the ore.

The streams of air, the products of combustio-n from the tiring furnaceand the products of combustion of the suliid on the hearth are takentogether in a miscellaneous gaseous mass through fiues to the stacks.

Some of the sulfur component is by the mere action of the heat alone,driven 0E in the form of a sublimate or`fume'; much of it is oxidizedand forms sulfur gases which are also carried away.

The volumes of air initially supplied have not, heretofore, been, andcannot, economically, be closely controlled. 4 The principal purpose hasbeen to insure merely that a large volume of air be introduced at thefiring end, supplemented by air introduced ,at points along the hearth,no attempt being made to relate the proportional quantities of thesulfur bodies and the air volumes that finally escape. Thechamber belowthe arch and above the orevis large, relatively, and the quantities ofair and gas indiscriminately vary, the air, however, al-

ways being largely in preponderance; the

alm being, as stated, to insure that a, very large amount of air shallbe introduced so that there will be assurance that the ore will b'eproperly affected by oxygen without regard to the surplus of air which,as well known, passes, in large volumes, o-n through the furnace to thestack.

The percentage of the sulfur component of the total gas volume thuscarried off in ordinary roasting furnaces is only from one to two percent., composed partly of sulfur fumes or sublimates and partly ofsulfur gases. vThese gas volumes containing suspended sulfur and sulfurgases, after being taken from the hearth chambers to the these volumesof gas, taken away from the Patented Feb. 13, 1917.

stacks, are delivered to the open atmosphere; h

ordinary roasters or furnaces,` is so low, ef-

forts tol neutralize or collect it entail such expense on the treatmentof the ore that they are not justified. But, if the p ercentage of thesulfur can, without increasing the expense of the ore treatment, beraised many times (say from one, or two, per cent. to nine or ten percent.) the expense incident to their collection is justified, and profitis derived from these by-products supplemental to the prot obtained.from the roasted metals.

The purpose of the present invention is to from external sources.

rial and the conditions are such as to provprovide a method oftreatment, first, whereby the desulfurizing of the ore can bebroughtclosely to the point where the desired predetermined ratiobetween the metallic components and the residue sulfur in the ore isreached, and, second, whereby the air initially introduced can beaccurately regulated in relation to the work of disassociating: thesulfur, and the ratio of the air relative to the volumes of sulfur gasesand fumes can be accurately controlled, and can be caused to carry offtherewith such a proportion of the sulfur that the effort to obtain thesulfur therefrom will be profitable. I first subject to a heatingtreatment a Amass of ore, Such as non-roasted ore, which of ore whichhas been more or less roasted or desulfurized. I cause the air and itscontents, during the second stage of treatment, to remove anotherpredetermined amount of the sulfur component, and, second, cause anincrease in the amount of sulfur gas in the total gas volume which istaken bfi" after the second stage.' I so proportion the variouscomponents of the masses and so determine their condition, that afterthe second stage the proportion of sulfur in the air will beso high thatit can be treated profitably in the ways above referred to.

Another object of the .invention is to make available, for heatgeneration, during a later stage of treatment, the' non-oxidized sulfurwhich is obtained as sublimate or fumes during an earlier stage oftreatment.

I prefer to produce all the heat necessary for carrying on the stepsabove mentioned by internal combustion, although it will be understoodthat more or less of the necessary heat can, at either stage be obtainedBut if the matevide for generating' all ofthe heat by interf nalcombustion, there is greater economy.

And if the second, or any later, step of treatment is keffected whilethe ore still contains heat generated by the earlier treatment, there isstill further economy. I find it advisable, frequently, to so operate asto have a higher heat generated during the second, or some later, stagethan during an earlier one because of the increasing difficulty indisassociating the sulfur after the release initially of the moreeasilydisassociated proportion. And this can be obtained by returningthe air to its second, or later, stage of work while still highlyheated, and, secondly, by so cordinatingl conditions that the sublimatesor fumes of metallic sulfur Will, at the second, or later, stage, serveas fuel external to the sulfur still combined with the metal in the ore.More or less of the sulfur initially contained in the native ore can, atdiscretion, be caused to pass 0E in such sublimated or fume form duringthe earlier stage. And sufhcient atmospheric oxygen can be delivered inthe first instance to provide not only that amount of oxygen which isnecessary to perform the predetermined oxidizing work in the earlierstage, but also a surplus amount of oxygen which, when it reaches the,second stage of activity, is sufficient to effect the burning oroxidizing of the metallic sulfur which is carried off .as sublimate orfume at the first stage; and

this can, under proper regulation, be utilized as a course of the highheat required to effect, at the second stage, the further disassociationof more or less of the residue sulfur still combined with the metal.And, of

course, this further oxidizing, at the second stage, of the nativesulfur component combined with the metal of the ore assists. in highlyheating the mass at said second stage.

Preferably the oxidizing at the second, or later,'stage of the freesulfur, drawn away at the first stage, is carried to the point,v

where it is all transformed into a sulfur gas, mainly sulfur dioxid.

With some materials I nd it advantageous to separate into two parts thetotal gas volume derived from the first treatment, one stream carryingthe main part of the sublimated or fumedfsulfur, and the other streamcarrying mainly completely oxidized sulfur. These two streams Iregulate, and relate to later actions according to conditions. -If theconditions are suitable I shunt the stream or volume of gas which ismost heavily laden with the sulfur gas (as dioxid) away from the orewhich is being subjected to the second treatment, and take it directlyto the receiver for the sulfur gas; and take the volume which ischargedmainly with free fume sulfur directly to the ore which is to be furtherdesulfurized depending upon its sulfur component for the generation ofheat and upon the surplus oxygen in this stream to effect'thepredetermined oxidizing at the second stage. l

Another object of the invention is to establish conditions such that notonly do I effect, first, the desulfurizing of the ore, and, second,produce a mass of by-produet gas which is highly enriched with sulfur,but also, third, deliver the solid ore in the form `of sinter blocks orcakes which possess all is vnow largely :manufactured Blast the matterwhichaelatefto the'sintering. offV the o're, anotherimportant' object islto prevent the explosi'onswhichare liable y.to oc cur where the airwithdrawn from 4theorethis in the ducts, whereit is a serious detri.l

ment.

My improved method of treating an ore masscan -be carriedon with eitherof several formsof apparatus. .In the drawings I have shown some ofthese.

Figure l is a side view of one of the mechanisms;

Flg. 2 is a top plan view of that shown 1n Figs. 3, 4 and 5 are,respectively, side views, more or less conventional in character, ofother forms of apparatus suitable for this purpose. p

In Figs.` 1 and 2,14 designates, as an entirety, a'now well knownmechanism adapted for use in roasting ores, and also sintering them. Itcomprises a track 2 with a series of ore-carrying pallets 3. These aremoved slowly in the' direction of the arrow a by vth usual mechanism,indicated by the Wheels at 4. Hoppers 5,A or equivalents, feed the oreto the pallets, and 6 indicates anigniter of Suitable sort.

After ignition the ore is supplied with air. A suction box 7, a duct 9,an exhaust mechanism 8 and a discharge duct 10 are provided for causingand sustaining interna-l combustion. These devicesare of predeterminedcapacities in relation to the ore, to its physical conditions, to itssulfur component and to the quantity of air that is to be passedtherethrough, all of these varying and requiring regulation.

By properly relating these air moving receiving and conducting devices Isucceed, at

. the outset, in raising to a high percentage the sulfur taken from theore, and, by selecting and properly co-relating all of the conditions,SecureV a proportion of sulfur (dioxid and sublimate) approximating liveto six per cent. This is in striking contrast with the gas mixtureobtained from the ordinary roasting hearths.

This fan 8 is connected by a pipe 10 with a hood 11, arranged over thosepallets that are situated between the pallets. above the air box 7 landthose at the discharge end of the apparatus which are about to delivertheir roasted and sintered contents.

The air and gases delivered I'to the hood` 11 are caused to pass throughthe ore contained in the pallets below the hood and into an air box 12,that is connected by pipe 13 with a fan 14 which discharges into a pipe-nine per cent. or more.

iltd tthlfs iii."'turnfdelivrs f'toitlle aPPawas designated where? thelgases sulfur ,which theycjariy.

to the patli offtiiavel of the pallets@ that edges come vc "fuite closeto the upper.' edges'of v the' pallets.: Thusja close joint permittingpractically nofleakage of gas maybeformed, although this.4 is not.necessary becauseV a Slight SPM@"nf1a-'y,often 'with advantage, lbeleft Abetween the edge'of'the .hood andthe edges. of the pallets. Thisisbecause,"in

practice, the amount of gas' discharged into the'hood 11, which isregulated by the, speed of the fan 8, is somewhat less than the amountof gas taken offby the suction caused by the fan 14. It follows .fromthis that some atmospheric lair will be drawn under the edges of thehood 11, thus preventing. the escape or leakage of y any sulfurous gas,

.-which leakage would bte-.objectionable and l -disagreeable In theapparatus just de-v of the ore, elemental sulfur in the form of asublimate. In these gases there is stillsufficient free oxygen to carryon the roasting operations in those pallets or ore receptacles thatoccupy the space between the hood 11 and the air box 12. The .gasestakenro-m the box 12 by the fan 14 and delivered" to apparatus 16 arefound to be much richer in sulfur dioxid than those taken from the air.box 7, the proportion being raised to Itis found that, in

an arrangement such as shown, the sulfurl v:which passes off into'theair box- 7 in the form of a sublimate, does not deposit in the pipes 9and 10, which are relatively short and are maintained at a hightemperature, but is delivered into the hood 11 and finally disappears inpassing through the ore contained in the pallets below the hood 1l, be-ving there oxidized. I

In Fig. 3 I have illustrated an apparatus in which are employednon-traveling con-- tainers for the ore during the roasting operations.Referring. tothis view, 17, 17

designate vindependent ore receivers, each mounted upon trunnions, 18,18so as to be free to be inverted, for dischargingA its conf tents.`-Means, either manual o'r 'power-op erated,.may be employed for'effecting the inverting operations of these orecQntainerS, suchmeansbeing typified by the crank han- `dles 19.

Each container has a perforated grate 20,

an ore-receiving space 21 above the grate, 'l

and an air box or chamber 22 vbelow the grate. The air chamber 22communicates 'l with the outside through one of the trunnions 18, whichis hollow.

23 represents the fan disposed between the containers 17 17 connected onone side by pipe 24, with the hollow trunnion 18 of the ore receiver 17,and on the 'other side, through pipe 25, with a hood 26 Vthat litsclosely over the upper end of the ore holder 17. This hood is movable upand down,

the pipe 25 having a slip joint connection to .permit this, in order toallow the hood to be lifted to expose the ore receiving portion of thecontainer to allow it to be filled, or to permit theholder as a whole tobe tilted for dischargin the roasted and sintered ore.

A pipe 2 leads from the hollow trunnion 18 of the ore holder 17 anddelivers the gases to a treating apparatus 16, not shown Vin this view,but similar to that'indicated in v and to permit v,the use ofthe hood 26.

The process as-carried out in the apparatus last described is similar tothat carried out in the apparatus shown in Figs. 1 and 2. It will beunderstood that the fan 23 operates to cause air to pass through thebody of ore contained in the holder 17 by suction and through the bodyof ore in the holder '17 by plenum. In using this appa- 'y ratus the orein the holder 17 should be ignited before that in the holder 17 isignited in order that the hood 26 may be brought to place beforesulfurous gases are delivered through the pipe 25.

In Fig. 4 I have represented another apparatus by which my invention maybe carried out. Here are indicated two apparatus A', A similar ingeneral principle t0 the apparatus illustrated in Figs. 1 and 2, whereare employed a series of moving pallets for carrying the ore. In theapparatus A air is induced to pass through the bodies of ore carried bythe pallets 3 by suction induced by a fan 28. The proportions of theapparatus and the speed at which its various parts are moved are soadjusted that a complete roasting and sintering of the ore takes placeduring the time any particular body or mass thereof is passing the airbox 7. In the apparatus A the plenum method of forcing the air throughthe ore is employed, the fanY 28 delivering to the' hood 29. The machineA is entirely distinct from the machine A', though the two apparatus arepreferably arranged close together so that the length of the ductsbetween them is reduced as much as possible.

In Fig. 5 I have illustrated another feav tureof my invention, appliedto an apparatus similar in general features to that indicated in Fig-1,similar reference letters being employed for similar parts in these twoviews, Figs. 1 and 5.

The air box 7 below the series of pallets nearest the i gniter isdivided into two chambers, 7 and 7, by a movable partition 30 arrangedto be manually a justed, as by means of a screw 31.l

It is found that the gasespassing from the masses of ore vnearest theigniter are relatively Weak in sulfur dioxid, but contain a lrelativelylarge amount of elemental sulfur in the form of sublimate. I thereforeconnect that chamber of the'air box 7 which is below'the pallets nearestthe igniter, designated 7 with the fan 8, and connect the outlet of thisfan with the hood 11, the same as in the apparatus illustrated inFig. 1. But the chamber 7 of the air box is connected by a ductv 18 withthe fan 14, which is also connected with the air box 12 located belowthose pallets covered by the hood 11. Thus the stronger gasesor thosecontaining a larger amount of sulfur dioxid, are delivered directly tothe fan`15 and by it to the apparatus 16 where the gas is treatl ed,only part of the gases from the air box 7 being delivered to the hood 11and causedl to pass a second time through a body or bodies of ignitedand sintering ore, to be freed of the sublimate which they carry, andenriched in sulfur dioxid. In using an apparatus such as shown in Fig. 5the position of the partition 30 is adjusted to suit the working of theapparatus.

If lead ores are treated according to the process and by means ofapparatus such asi here described and illustrated, the gases will carrymore or less volatilized lead or lead fume. A considerable portion ofthis will be recovered when the gases pass through Aa second bed ofignited and sintering ore, the same as it takes up and recovers thesulfur sublimate, as already described; for the semi-fused silicateswill absorb and hold whatever load fume comes in contact with themduring the passage of the gases. The loss of lead may thus be diminishedto a very considerable extent.

I do not in this case claim the novel apparatus herein described, butreserve to myself the right to make'that the subject-matter of anotherapplication which I proposeto lile as a division of this case.

What I claim is 1. The herein described method of treattaneouslyobtaining a uniformly porous sin-1 ter, the same consisting in exposingthe sulfid orev in a relatively shallow layer or stra- -said air withits sulfur contents again through the sintered ore and oxidizing more orless of the sulfur residue therein, charging the air volume with thesulfur gases derived therefrom.

2. The herein described method of treat- .ing suld ores to. obtain fromthem simultaneously with the formation of a porous sinter, a gas rich insulfur and sulfur products, which method consists in subjecting layersor straita of ore to ignition and supplying combustion-supporting air attwo stages thereto after ignition, the air supplied during the secondstage being of the same Character as that which `is delivered to the oreduring the first stage.

3. The herein described method of roasting sulfid ores, whereby a poroussinter is obtained together with gaseous products of combustion rich insulfur content, which consists in arranging ore in shallow layers,igniting it, passing air through said layers to remove or consume sulfurfound therein, and collecting and returning said air and the gases ofcombustion to said ore,in order to complete the burning of the containedsulfur. whereby the gases of combustion thus obtained being charged withsulfur dioxid from the two passages through the sulfur layer, are richin sulfur products.

4. The herein described method of roasting sulfid ores, whereby a poroussinter is obtained together with gaseous products of combustion rich insulfur content, which consists in arranging ore in shallow layers,igniting it, passing air through said layers to remove 'or consumesulfur found therein, and collecting and returning said air and thegases of combustion to said ore while said ore is still hot, in order tocomplete the burning of the contained sulfur, whereby the gases ofcombustion thus obtained being charged with sulfur vdioxid from the twopassages through the sulfur layer,are rich in sulfur products.

5. The herein described method of roasting sulid ores, whereby a poroussinter is obtained together with gaseous products of combustion rich insulfur content, which consists in arranging ore in shallow layers,igniting it, passing air through said layers to remove or consume sulfurfoundtherein,

and collecting and returning said air and the gases of combustion tosaid ore while both the ore and the air and gases of combustion arestill hot, in order to complete the burning of the contained sulfur,whereby the gases of combustion thus obtained being charged with sulfurdioxid from the two passages through the sulfur layer, are rich insulfur products.

6. The herein-described method of treati ing ore containing acombustible component which consists in arranging said ore in layerform, progressively moving it, igniting it, supplyingcombustion-supporting air thereto after ignition, subsequently returningthe said air at a second stage and again causing it to pass in contactwith the ore while the latter is still hot, and collecting the gasesgenerated during the said second sta e.

'7g The herein described method of treating ore containing sulfur, whichconsists in arranging said ore in layer form, giving to said ore soarranged a progressive movement, igniting said ore, passing air throughsaid ore in a current, regulated as to speed and passing them a secondtime through the,

progressing layer of ore, whereby an air current laden with sulfur gasesin high proportion is obtained.

8. The herein described process which consists in passing more than oncethrough a progressing layer of burning o're, the order of said passagesbeing in the same general directions as that in which the ore moves, acurrent of air.

9. The process which consists in establishing a moving layer ofsulfur-bearing ore, igniting said ore at a given point in its traverse,passing through said ignited and moving layer for a given extent of thetraverse a current of an oxidizing agent, whereby by the heat of areaction, said agent and said ore become heated, and at a further stagein the traverse of the ore layer and while it is still hot passing thesame hot current of oxidizing agent through said layer, whereby, owingto the heated conditions specified, the sulfur becomes completelyoxidized.

l0. r1`he herein described method of treating ore containing sulfur,which consists in arranging said ore in layer form, giving to said oreso arranged a progressive movement, igniting said ore, passing airthrough said ore within adelined extent of forward progress of the ore,in a current, dividing said current, passing the forward part of saidcurrent ldirectly to an apparatus for recovery of the sulfur gases, andpassing the rearward part of the current again through a mass ofprimarily roasted ore.

l1. The herein described method of treating ore containing sulfur, whichconsists in arranging said ore in layer form, giving to said ore soarranged a progressive movement, ignting said ore, passing air throughsaid ore within a defined extent of forward progress of the ore, in acurrent, dividing said current, passing the forward part of said currentdirectly to an apparatus for recovery of the sulfur gases, passing therearward part of the current again' through a mass of primarily roastedore, and conducting the resultant gases and products of e0m-.

10 bustion to mingle'with the gases and prodsulfur may be takenat oneoperation froml both divisions of the current.

In testimony whereof, I have aHiXed my 15 signature, in presence of twowitnesses.

v ARTHUR S. DWIGHT. Witnesses HENRY J. STEHLI, JOSEPH C. BENSON.

